Dozens of mortar shells and rockets are on display after being seized from the Klos-C civilian cargo ship that Israel intercepted last Wednesday off the coast of Sudan, at a military port in the Red Sea city of Eilat, southern Israel, Monday, March 10, 2014.

Israel claims the M-302s were flown from Syria to Iran before being loaded aboard the Panamanian-flagged ship in an Iranian port. This raises the question of why Iran would ship Syrian-made rockets – allegedly to Hamas in the Gaza strip – when it produces its own. The answer lies in the increasingly close links between Syria and Iran in rocket research, development, and production, and in Syria's success in expanding the reach of its arsenal.

"The Syrian rocket industry is quite capable. They can make up their own design. You see already in the civil war that they know their stuff," says Uzi Rubin, an Israeli expert on missile defense and the founder and director of a defense ministry program on long-range missiles.

Syria began investing in a strategic rocket arsenal in the early 1980s, recognizing that its Soviet-equipped army was no match for its arch enemy Israel. To counter Israel's superior conventional forces, Damascus acquired ballistic missiles, such as the Scud, and began developing chemical-filled warheads.

The industry expanded as Syria and its ally Iran drew closer under Syrian President Bashar al-Assad, who came to power in 2000. The two countries signed a mutual defense pact in 2006 and an additional military cooperation agreement the following year.

Since 2000, Syria has become a major supplier of mid-range rockets such as 220-mm Urugans and the M-302s – one of the rockets seized by Israel – to Hezbollah, the Iranian-equipped Shiite militant group in Lebanon. During its 2000 war with Israel, Hezbollah fired mostly Syrian-made rockets into Israel. Its deepest penetration was a M-302 strike on the Israeli city of Hadera, 50 miles south of the border with Lebanon.

Since then, Syria has developed variations of the M-302, a testament to its acumen, Mr. Rubin says. The latest version is capable of reaching 134 miles, although the versions of the M-302 discovered on the Klos-C had ranges between 55 to 100 miles, longer than Iranian-made Fajr rockets. Israeli officials say this range would enable militants in Gaza to fire rockets at Jerusalem and Tel Aviv.

Rocket science

The state-run Syrian Scientific Research Center is responsible for rocket research and development, including surface-to-air missiles. According to Jane’s Defense Weekly, Syria is researching solid-fueled rockets that would be quicker to launch and harder to detect in advance. These rockets are more practical for groups like Hezbollah given Israel's regular surveillance by jets and pilotless drones. Liquid-fueled missiles, such as Scuds, require a lengthy launch preparation time that make them easier to spot.

After the 2006 war between Israel and Hezbollah, Syria stepped up production of longer-range missiles, including the M600 rocket, a Syrian version of Iran’s Fateh-110. The M600, which reportedly was transferred to Hezbollah in 2009, can carry a 1,100-pound warhead for 150 miles and is fitted with a guidance system that is accurate within 500 yards at maximum range.

Syria usually reveals little about its rocket capabilities, conducting tests and military exercises out of the public eye. However, since the anti-Assad uprising began three years ago, the regime has staged several televised exercises involving most of its rocket and missile arsenal.

The 2011 NATO airstrikes in Libya may be a factor, says Rubin. "[Syria] wanted to show that they have better stuff than [former Libyan leader] Qaddafi and warn off the West."